Transformer



"April 10, 1934.

J. A. COMSTOCK ,954,557

TRANSFORMER Filed June 28, 1953 2 Sheets-Sheet l W/ 7716558. 26 INVENTOR.

ATTORNEY.

I Patented Apr. 10, 1934 TRANSFORMER James A. Comstock, Cleveland, Ohio, assignor to The Acme Electric & Manufacturing Company, Cleveland, Ohio, a corporation of Ohio Application June 28, 1933, Serial No. 678,047

9 Claims.

My invention relates to transformers and more particularly to transformers having a high leakage reactance.

There are a great number of applications that call for transformers having a high leakage reactance which gives a relatively high secondary voltage at no loadwith a resulting decrease in the secondary voltage under load, thus effecting a substantially constant current output. One of 10 such applications is the heating of the filament of a large radio transmitting tube. The resistance of the filament when cold is relatively small compared to the resistance when hot. Consequently, the cold resistance amounts almost to a short cirl5 cuit condition on the transformer, and it is neces-- sary to limit the current to avoid damage to the filament while it is warming up. Another grow ing and important application that calls for transformers having a high leakage reactance is the lighting of neon or other gaseous tubes. It is in this connection that I have illustrated my invention, but it is to be understood that I do not intend to limit my invention to this application.

The operating characteristics of gaseous tubes are such that they require a relatively high initial voltage to ionize the gas, but only a relatively low operating voltage after the gas is once ionized.

Therefore, an object of my invention is the provision of a transformer which, when connected in circuit relation with a gaseous tube, gives a relatively high initial voltage to ionize the gas of the tube and a relatively low operating voltage after the gas is once ionized.

Another object of my invention is to provide for limiting and regulating the amount of flux which interlaces the secondary windings in accordance with the current flowing through the said windings.

A further object of my invention is to provide for by-passing a portion of the flux that interlaces the secondary windings in accordance with the current flowing through the said windings.

A still further object of myinvention is to provide for limiting the short circuited current of either one of two secondary windings while, at

the same time, keeping the other secondary winding in an operative condition.

Another object of :my invention is the provision of a balancing shunt which by-passes a por- J tion of the flux when the electrical load of the two secondary windings are unequal and which thus tends to re-establish a balanced electrical load on each secondary winding.

Another object of my invention is the provision of a balancing shunt which, because of its balancing effect in maintaining substantially a balanced load on the secondary windings, makes the operating characteristics of the transformer such that a gaseous tube of a given length and of a given characteristic operates with a. lower flickering voltage than that which the same gaseous tube would operate with a transformer having no balancing shunt.

Other objects and a better understanding of my invention may be had by referring to the following description, taken in connection with the accompanying drawings, in which like reference characters represent like parts and in which:

l 'ig. 1 represents a side elevational view of a high reactance transformer embodying features of my invention;

Fig. 2 represents a cross-sectional view, in elevation of the transformer shown in Fig. 1;

Fig. 3 represents a plan view of the transformer shown in Fig. 1;

Fig. 4 is a diagrammatical view of my transformer, shown in circuit relation with two gaseous tubes;

Fig. 5 is a diagrammatical view of a modified form of my transformer, shown in circuit relation with two gaseous tubes; and

Fig. 6 is a chart showing the performance of my transformer as compared to that of a transformer in which there is no balancing shunt.

- With reference to Figs: 1, 2 and 3, my transformer comprises, in general, a magnetic circuit 10, two primary windings P1 and P2, two secondary windings S1 and S2, two magnetic shunts A and C which function to limit the secondary current, and a balancing shunt B, which functions to maintain a substantially balanced load on the secondary windings.

As illustrated, the magnetic circuit 10 is of the core type with the primary and the secondary windings mounted upon the upper longitudinal legs thereof, as viewed in the drawings. In accordance with the usual practice in constructing transformers, the magnetic core 10 is built up of a plurality of stacked laminations. In this embodiment of the invention, the main part of the magnetic core 10 is made up of a plurality of 1 U-shaped laminations with the opened end there-,

of bridged by a laminated rectangular block 11. As shown best in Fig. 3, for the purpose of securing the magnetic block 11 against the ends of the stacked U-shaped laminations, the outer U-shaped laminations 12 are reversed so that in addition to their constituting a part of the magnetic circuit they constitute straps to which the magnetic block 11 maybe secured by the rivets 14 or by any other suitable means such as by welding.

To keep the cross-sectional area of themagnetic core substantially uniform throughout its length, the reduced area at the left-hand end of the core, caused by the reversal of the U- shaped laminations 12, may be built up by rectangular laminations 13 riveted to the opposite sides of the reduced section by the rivets 14, at the same time that the main U-shaped laminations are riveted together. In assembling the transformer, the primary and secondary windings are placed upon the upper leg of the U- shaped core before the laminated rectangular block 11 is riveted across the end of the opening thereof. While the construction of the magnetic core 10 is simple and'easy to assemble, it is to be understood that I do not intend to limit my invention to the illustrated embodiment, for any'other suitable magnetic circuit may be employed.

In accordance with my invention, the primary and the secondary windings are placed in spaced relation, upon the upper leg of the magnetic core 10 in the following order, reading from left to right; first, the primary winding P1; second, the secondary winding S1; third, the secondary winding S2, and fourth, the primary winding P2. Positioned between the primary winding P1 and the secondary winding S1 is a magnetic shunt A; betweenthe secondary winding S1 and the secondary winding S2 is a magnetic shunt B, and between the secondary winding, ,S2 and the primary winding P2 is a magneticshunt C. In this invention, the magnetic shunts A and C may be designated as current limiting shunts and the magnetic shunt B may bed'esignated as a balancing shunt. To accomplish their desired result, themagnetic shunts each have a higher reluctance than the main magnetic core 10. This maybe efiected either by inserting nonmagnetic spacers 22 between the ends of the magnetic shunts and the inner surface of the main magnetic core, or by varying the crosssectional area of the shunts themselves. As illustrated best in Fig. 2, the windings are suitably insulated from the magnetic core 10 and the magnetic shunts by means of insulating members 21. In addition to acting as insulating barriers, the insulating members 21 also act as spaces or wedges for rigidly holding the windings upon the magnetic core 10.

The primary 'windings P1 and P2 may be connected series aiding, or they may be connected parallel aiding. The secondary coils S1 and S2, in either case, are connected series aiding. In the preferred form of my invention, shown in Figs. 1, 2, 3 and 4, the primary windings are connected series aiding by a conductor 26 and the secondary windings are connected series aiding by a conductor 2'7, which, in turn, is connected to a ground 40.

With reference to Fig. 4, which shows a diagrammatical view of my transformer, connected in circuit relation with two gaseous tubes 30 and 31, the operation of my transformer may be explained in the following manner:

First, let it be assumed that the primary supply switch 32 has just been closed. Immediately upon closing the switchftheprimary windings P1 and P2, establish a primary flux that flows around the entire main magnetic core 10, with substantally none of the fiux flowing through the magnetic shunts. This primary flux induces a rela-' tively high voltage in both of the secondary windings S1 and S2, which ionizes the gas and thus illuminates the two gaseous tubes 30 and 31. Just as soon as the gas of the tubes is ionized, its electrical resistance immediately becomes relatively low, and thus a relatively large secondary current tends to flow through the secondary windings S1 and S2. Concurrently with a sudden rise in the secondary current, the secondary windings Sl'and S2, establish a secondary flux that opposes the passage of the primary flux through the secondary windings. Because of the opposition of the secondary flux, the primary flux emanating from the primary windings P1 and P2 is constrained to flow respectively through the magnetic shunts A and C. The by-passing of the primary flux through the magnetic shunts A and C thus reduces the voltage induced in the secondary windings S1 and S2 to a value which bears a relation to that portion of the primary flux still interlacing the secondary windings. This reduction in the secondary voltage, in turn, limits the value of the secondary current. The degree 'to which the secondary current is limited depends upon the reluctance of the magnetic shunts A and C and upon the design and proportions of the various other co-acting parts of the'transformer. The resultant efiect of the two magnetic .shunts A and C is such that, after the gas of the gaseous tubes is ionized, the relatively high initial secondary voltage is immediately and automatically reduced to its normal operating value.

So long as the electrical load of each of the secondary windings S1 and S2 is the same, the balancing shunt B by-passes substantially no flux, if any. This is the condition when the two gaseous tubes 30 and 31 are passing the same amount of current. Let it now be assumed that a ground occurs at the lower electrode 33 of the gaseous tube 31. This means that the secondary winding S2 is now short circuited, and that the secondary current of the secondary winding S2 immediately tends to rise to a high Value, which if not limited to a safe value will burn out the winding S2. Under this short circuited condition, the magnetic shunt C by-passes substantially all, or a major part, of the primary flux emanating from the primary winding P2. Also, because of the strong opposing effect of the secondary flux set up by the secondary winding S2, under this short circuited condition, the primary flux emanating from the primary winding P1 is constrained to pass through the balancing shunt B. As aresult, the secondary current of the secondary winding S2 is limited to a safe value, while, at the same time, the normal operation of the secondary winding S1 is unimpaired. This means that the gaseous tube 30 continues to operate even though the secondary winding S2 is short circuited. The

same, but a 'reverse short circuited condition arises, should a ground occur at the lower electrode 34 of the gaseous tube 30. Under this condition, the primary flux emanating from the primary winding P1 is by-passed through the magnetic shunt A, and the primary flux emanating from the primary winding P2 is by-passed through the magnetic shunt B. As a result, the short circuited current of the secondary winding-S1 is v 1,954,557 reluctance of the magnetic shunt B, the larger the short circuited current of the secondary.

The action of the balancing shunt B is the same, but of a smaller degree, when the electrical load of the secondary windings is unequal, as will be the case when the operating characteristics of the two gaseous tubes 30 and 31 are not the same. Under cases of an unequal load. on the secondary windings S1 and S2, the balancing shunt B tends to re-balance the electrical load by by-passing a portion of the flux. This re-bal'ancing action not only gives improved operation but also makes it possible to operate a gaseous tube of a givenlength and of a given characteristic at alower flickering voltage (that is the voltage at which a given tube just begins to flicker) than at which the tube could be operated with a transformer having no balancing shunt.

With reference to the chart of Fig. 6, the flickering volts are plotted as ordinates and the length of a given gaseous tube is plotted as abscissa. The full line represents a transformer having a balancing shunt and the dotted line represents a transformer having no balancing shunt. Tests show that a gaseous tube of a given length and of a given characteristic operates with a lower flickering voltage when connected to a transformer having a balancing shunt than when connected to a transformer having no balancing shunt. This means that a great deal of the flickering" of gaseous tubes is, minimized. \w

In Fig. 5, I illustrate a modified arrangement 1 of windings, in that the position of the secondary windings and the primary windings are interchanged. Also, the primary windings are connected in parallel aiding. The general results obtained by this modification are substantially the same as that explained in relation to the preferred form of my invention.

Although I have describedvmy invention with a certain degree of particularity, it is understood that the present disclosure has been made only by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from thespirit and scope of the invention as hereinafter claimed.

I claim as my invention: 7

l. A transformer that is adapted to energize an electrical load having a variable resistance comprising, in combination, a rectangular magnetic core having two relatively long legs interconnected by two relatively short ends, a primary winding disposed to surround a portion of one of the legs of the magnetic core, a secondary winding associated in spaced relation with the primary winding and disposed to surround another portion of the leg upon which the primary winding is mounted, said portion being designated as the secondary core portion, a magnetic shunt disposed between the primary winding and the secondary winding and arranged to bridge magnetically the space between the two legs of the magnetic core, said magnetic shunt being adapted, when the secondary core portion has a relatively low secondary flux opposing the passage of the primary flux produced by the primary winding,

to provide a negligible by-pass for'the flux pro-- duced by the primary winding, thereby causing the induction of a relatively high voltage in the secondary winding, and said magnetic shunt being adapted, when the secondary core portion has a relatively high secondary flux opposing the passage of the primary flux produced by the primarywinding, to provide 'an appreciable bypass for the flux produced by the primary winding, thereby reducing the voltage induced in the secondary winding with the result that the reluctance of the secondary core portion varies substantially inversely with changes in the resistance of the electrical load, a second primary winding disposed to surround another portion of the leg upon which the first-mentioned primary and secondary windings are mounted, a second secondary winding associated in spaced relation with the second-mentioned primary winding and disposed to surround another portion of the leg upon which the other windings are mounted, said portion being designated-as the second-mentioned secondary core portion, a second magnetic shunt disposed between the second-mentioned primary winding -and the second-mentioned secondary winding and arranged to bridge magnetically the space between thetwo legs of the magnetic core, said second-mentioned magnetic shunt being adapted, when the second-mentioned secondary core portion has a relatively low secondary flux opposing the passage of the primary flux produced by the second-mentioned primary winding, to provide a negligible by-pass for the flux produced by the second-mentioned primary winding, thereby causing the induction of a relatively high voltage in the second-mentioned secondary winding, and said second-mentioned magnetic shunt being adapted, when the. second-mentioned secondary core portion has a relatively'high secondary flux opposing the passage of the primary flux produced by the second-mentioned primary winding, to provide an appreciable by-pass for the flux produced by the second-mentioned primary winding, thereby reducing the voltage induced in the second-mentioned secondary winding with the result that the reluctance of the second-mentioned secondary core portion varies substantially inversely with changes in the resistance of the electrical load, and a balancing magnetic shunt disposed between the two secondary windings and arranged to bridge magnetically the space between the two legs of the magnetic core, said balancing shunt being adapted, when the two secondary core portions have substantially the ,same value of secondary flux opposing the passage of the primary flux produced by the two primary windings to provide a negligible by-pass for the flux produced by the two primary windings, and said balancing shunt being adapted, when the two secondary core portions have an unequal value of secondary flux opposing the passage of the flux producedwinding surrounding the secondary core portion having the higher value of opposing secondary flux and to induce a relatively low voltage therein, and causing a'relatively large amount of the said primary flux to interlace the said secondary winding surrounding the secondary core portion having the lower value of opposing secondary flux, and to induce a relatively high'voltage in the said secondary winding and thus keeping the said secondary winding in bperation for energizing its electrical load.

2. A transformer that is adapted to energize an electrical load having a variable resistance netic core having two relatively long legs interconnected by two ,relativelyshort ends, a primary winding. disposed to surround a portion of one of the legs of the magnetic core, a secondary winding associated in spaced relation with the primary winding and disposed to surround another portion of thevleg upon which the primary I winding is mounted, said portion being designat ed as the secondary core portion, amagnetic shunt disposed between the primary winding and the secondary winding and arranged to bridge magnetically thespace betweenthe two legs of 'the magnetic core, said magnetic shunt includprimary flux produced by the primarywinding,

to provide an appreciable by-pass for the flux produced by the primary winding, thereby reducing the voltage induced in the secondary winding with the result that the reluctance of the secondary core portion varies substantially inversely with changes in the resistance of the electrical load, a second primary winding disposed to surround another portion of the leg upon which the first-mentioned primary and secondary windings are mounted, a second secondary winding associated in spaced relation with the secondmentioned primary winding and disposed to surround another portion of the leg upon which the other windings are mounted, said portion being designated as the second-mentioned secondary core portion, a-second magnetic shunt disposed between the second-rnentioned primary winding and the second-mentioned secondary winding and arranged to bridge magnetically the space be-' tween the two legs of the magnetic core, said second-mentioned magnetic shunt including an air gap and being adapted, when thesecond-mentioned secondary core portion has a relatively low secondary flux opposing the passage of the primary flux-produced by the second-mentioned primary winding, to, provide a negligible by-pass for the flux produced by the second-mentioned primary winding, thereby causing the induction of a relatively high voltage in the second-mentioned secondary winding, and said second-mentioned magneticshunt being adapted, when the second-mentioned secondary core portion has a relatively high secondary fluxopposing the passage of the primary fiux produced by the secondmentioned primary winding, to provide an appreciable by-pass for the flux produced by the second-mentioned primary winding, thereby reducing the voltage induced in the second-mentioned secondary winding with the result that the reluctance of the second-mentioned secondary core portion varies substantially inversely with changes in the resistance of the electrical load,

and a balancing magnetic shunt disposed between the two secondary windings and arranged to bridge ,magnetically the space between the two legs of the magnetic core, said balancing shunt including an air gap and being adapted, when the two secondary core portions have substantial- ,ly the same value of secondary flux opposing the for the flux produced by the two primary windings', and said balancingshunt being adapted. when the two secondary core portions have an unequal value of secondary flux opposing the pasrounding the secondary core portion having the lower value of opposing secondary flux, thereby causing a relatively small amount of the said primary flux to interlace the secondary windin surrounding the secondary core portion having the higher value of opposing secondary flux and to induce a relatively low voltage therein, and causing a relatively large amount of the said primary flux to interlace the said secondary winding surrounding the secondary core portion having the lower value of opposing secondary flux and to induce a relatively high voltage in the said secondary winding and thus keeping the said secondary winding in operation for energizing its electrical load.

3. A transformer that is adapted to energize an electrical load having a variable resistance comprising, in combination, 'a rectangular magnetic core having two relatively long legs interconnected by two relatively short ends, a primary winding disposed to surround a portion of one of the legs of the magnetic core, a secondary winding associated in spaced relation with theprimary winding and disposed to surround another portion of the leg upon which the primary winding is mounted, said portion being designated as the secondary core portion, a magnetic shunt disposed between the primary winding and the secondary winding and arranged to bridge magnetically the space between the two legs of themagnetic core, said magnetic shunt being adapted, when the secondary core portion has a reatively low secondary flux opposing the passage of the primary flux produced by the primary winding, to provide a negligible by-pass for the flux produced by the primary winding, thereby causing the induction of a relatively high voltage in the secondary winding, and said magnetic shunt being adapted when the secondary core portion has a relatively high secondary flux opposing the passage of the primary flux produced by the primary winding, to provide an appreciable by-pass for the flux produced by the primary winding, thereby reducing the voltage induced in the secondary winding with the result that the reluctance of the secondary core portion varies substantially inversely with changes in the resistance of the electrical load, a second primary winding disposed to surround another portion of the leg upon which the first-mentioned primary and secondary windings are mounted, a second secondary winding associated in spaced relation with the second-mentioned primary winding and disposed to surround another portion of the leg upon which the other windings are mounted, said portion being designated as the second mentioned secondary core portion, a, second magnetic shunt disposed between the second mentioned primary winding and the second-mentioned secondary winding and arranged to bridge magnetically the space between the two legs of the magnetic core, said second-mentioned magnetic shunt being adapted, when the second-mentioned secondary core portion has a relatively low secondary flux opposing the passage of the primary flux produced by the second-mentioned primary winding, to provide a negligible by-pass for the flux ing, thereby causing the induction of a relatively high voltage in the second-mentioned secondary winding, and said second-mentioned magnetic shunt being adapted, when the second-mentioned secondary'core portion has a relatively high secondary flux opposing the passage of the primary flux produced by the second-mentioned primary winding, to provide an appreciable by-pass for the flux produced by the second-mentioned primary winding, thereby reducing the voltage induced in the second-mentioned secondary winding with the result that the reluctance of the second-mentioned secondary core portion varies substantially inversely with changes in the resistance of the electrical load, and a balancing magnetic shunt disposed between the two windings of like characteristics and arranged to bridge magnetically, the space between the two legs of the magneticcore, said balancing shunt being adapted, when the two secondary core portions have substantially the same value of secondary flux opposing the passage of the primary flux produced by the two primary windings, to provide a negligible by-pass for the flux produced by the two primary windings, and said balancing shunt being adapted, when the two secondary core portions'have an unequal value of secondary flux opposing the passage of the flux produced by the two primary windings, to provide an appreciable by-pass for the flux produced by the primary winding that is associated with the secondary winding surrounding the secondary core portion having the lower value of opposing secondary flux, thereby causing a relatively small amount of the said primary flux to interlace the secondary winding surrounding the secondary core portion hava ing the' higher value of opposing secondary flux and to induce a relatively low voltage therein, and causing a relatively large amount of the said primary flux to interlace the said secondary winding surrounding the secondary core portion having the lower value of opposing secondary flux, and to induce a relatively high voltage in the said secondary'winding and thus keeping the said secondary winding in operation for energizing its electrical load. -4. A transformer that is adapted to energize an electrical load having a variable resistance comprising, in combination, a rectangular magnetic core having two relatively long legs inter connected by two relatively short ends, a primary winding disposed to surround a portion of one of the legs of the magnetic core, a secondary winding associated in spaced relation with the primary winding and disposed to surround another portion of the leg upon which the primary winding is mounted, said portion being designated as the secondary core portion, a magnetic shuntdisposed between the primary winding and the secondary winding and arranged to bridge magnetically the space between the two legs of the magnetic core, said magnetic shunt being adapted, when the secondary core portion has a relatively low secondary flux opposing the passage of the primary flux produced by the primary winding, to provide a negligible by-pass for the flux produced by the primary winding, thereby causing the induction of a relatively high voltage in the secondary winding, and said magnetic shunt being adapted -when the secondary core portion has a relatively high secondary flux opposing the passage of the primary flux produced .by the primary winding,'to provide an appreciable by-pass for the flux produced by the primary winding and disposed to surround another portion of the leg upon which the other windings are mounted, said portion being designated as the second mentioned secondary core portion, means for grounding one end of each of the secondary windings, means for connecting an electrical load between the grounding means and each of the other ends of the secondary windings, a second magnetic shunt disposed between the second mentioned primary winding and the second-mentioned secondary winding and arranged to bridge magnetically the space between the two legs of the magnetic core, said secondmentioned magnetic shunt being adapted, when the second-mentioned secondary core portion has a relatively low secondary flux opposing the passage of the primary flux produced by the second-mentioned primary winding, to provide a negligible b y -pass for the flux produced .by the second-mentioned primary winding, thereby causing the induction of a relatively high voltage in the second-mentioned secondary winding, and said second-mentioned magnetic shunt being adapted, when the second-mentioned secondary core portion has a relatively high secondary flux opposing the passage of the primary flux produced by the second-mentioned primary winding, to provide an appreciable by-pass for second-mentioned secondary core portion varies substantially inversely with changes in the resistance of the electrical load, and a balancing magnetic shunt disposed between the two windings of like characteristics and arranged to bridge magnetically, the space between the two legs of the magnetic core, said balancing shunt being adapted, when the two secondary core portions have substantially the same value of secondary flux opposing the passage of the primary flux produced by the two primary windings, to

provide a negligible by-pass for the flux produced by the two primary windings, and said balancingshunt being adapted, when the two secondary core portions have an unequal value of secondary flux opposing the passage of the flux produced by the two primary windings, to provide an appreciable by-pass for the flux produced by the primary winding that is associated with the secondary winding surrounding the secondary core portion having the lower value of opposing secondary flux, thereby causing a relatively small amount of the said primary flux to interlace the secondary winding surrounding the secondary core portion having the higher value of opposing secondary flux andto induce a relatively low voltage therein, and causing a relatively large amount of the said primary flux to interlace'the said secondary winding 'surrounding the secondary core portion having the lower value of opposing secondary flux, and to induce a relatively high voltage in the aid secondary winding and thus keepingthe said secondary winding in operation for energizing its electrical load.

A transformer that is adapted to energize an electrical load having a variable resistance comprising, in combination, a magnetic core having a relatively long winding portion, a primary winding disposed to surround a part of the winding core portion, a secondary winding associated in spaced relationwith the primary winding and disposed to surround another part of the winding core portion, magnetic shunt means having a relatively high reluctance disposed between the primary winding and the secondary winding, a second primary winding disposed to surround another part of the winding core portion, a second secondary winding associated in spaced relation with the second-mentioned primary winding and disposed to surround another portion of the winding core portion, second magnetic shunt means having a relatively high reluctance disposed between the second mentioned primary winding and the secondmentioned secondary winding, and balancing magnetic shunt means disposed between the two windings of like characteristics, the magnetic reluctance of the balancing magnetic shunt means being greater than the magnetic reluctance of either of the other two shunt means.

6. A transformer that is adapted to energize an electrical load having a variable resistance comprising, in combination, a magnetic core having a relatively long winding portion, a primary winding disposed to surround a portion of the winding core portion, a secondary winding associated in spaced relation with the primary winding and disposed to surround another portion of the winding core portion, said portion being designated as the secondary core portion, a magnetic shunt disposed between the primary winding and the secondary winding, said magnetic shunt being adapted, when the secondary core portion has a relatively low secondary flux opposing the passage of the primary flux produced by the primary winding, to provide a negligible by-pass for the flux produced by the primary winding, thereby causing the induction of a relatively high voltage in the secondary winding, and said magnetic shunt being adapted when the secondary core portion has a relatively high secondary flux opposing the passage of the primary flux produced by the primary winding to provide an appreciable bypass for the flux produced by the primary winding, thereby reducing the voltage induced in the secondary winding with the result that the reluctance of the secondary core portion varies substantially inversely with changes in the resistance of the electrical load, a second primary winding disposed to surround another portion of the winding core portion, a second secondary winding associated in spaced relation with the secondmentioned primary winding and disposed'to surround anotherportion of the winding core portion, said portion being designated as the secondmentioned secondary core portion, a secondmagnetic shunt disposed between the second mentioned primary winding and the second-mentioned secondary winding, said second-mentioned magnetic shunt being adapted, when'the second-mentioned secondary core portion 'has a relatively low secondary flux opposing the passage of the primary flux produced by the second-mentioned primary winding, to provide a negligible by-pass for the flux produced by the second-mentioned primary winding, thereby causing the induction of a relatively high voltage in the second-mentioned secondary winding, and said second-mentioned magnetic shunt being adapted, when the secondmentioned secondary core portion has a relatively high secondary ilux opposing the passage of the primary flux produced by the second-mentioned primary winding, to provide an appreciable bye pass for the flux produced by the second-mentioned primary winding, thereby reducing the voltage induced in the second-mentioned secondary winding with the result that the reluctance of the second-mentioned secondary core portion varies substantially inversely with changes in the resistance of the electrical load, and a balancing magnetic shunt disposed between the two primary windings, said balancing shunt being adapted, when the two secondary core portions have substantially the same value of secondary flux opposing the passage of the primary flux produced by the two primary windings, to provide a negligible by-pass for the flux produced by the two primary windings, and said balancing shunt being adapted, when the two secondary core portions have an unequal value of secondary flux opposing the passage of the flux produced by the two primary windings, to provide an appreciable by-pass for the flux produced by the primary winding that is associated with the secondary winding surrounding the secondary core portion having the lower value of opposing secondary flux, thereby causing a relatively small amount of the said primary flux to interlace the secondary winding surrounding the secondary core portion having the higher value of opposing secondary flux and to induce a relatively low voltage therein; and causing a relatively large amount of the said primary flux to interlace the said secondary winding surrounding the secondary core portion having the lower value of opposing secondary flux, and to induce a relatively high voltage in the said secondary winding and thus keeping the said secondary winding in operation for energizing its electrical load.

' '7. A transformer that is adapted to energize an electrical load having a variable resistance comprising, in combination, a magnetic core having a relatively long winding portion, a primary winding disposed to surround a portion of the winding core portion, a secondary wind'ng associated in spaced re ationwith the primary winding and disposed o surround another portion of the winding core portion, said portion being designated as the secondary core portion, a magnetic shunt disposed between the primary winding and the secondary winding, said magnetic shunt being adapted, when the secondary core portion has a relatively low secondary flux opposing the passage of the primary flux produced by the primary winding, to provide a negligible, by-pass for the flux produced by the primary winding, thereby causing the induction of a relatively high voltage in the secondary winding, and said magnetic shunt being adapted when the secondary core portion has a relatively high secondary flux opposing the passage of the primary flux produced by the primary winding, to provide an appreciable by-pass for the flux produced by the primary winding, thereby reducing the voltage induced in the secondary winding with the result that the reluctance of the secondary core portion varies substantial y inversely with changes in the resistance of he electrical load, a 'second primary winding disposed to surround another portion of the winding core portion, a second secondary winding assoc ated in spaced relation with the second-men tioned primary winding and disposed to surround another portion of the winding core portion, said portion being designated as the second-mentioned secondary core portion, means for grounding one end of each of the secondary windings, means for connecting an electrical load between the ground- .ing means and each of the other ends of the secondary windings, a second magnetic shunt disposed between the second mentioned primary winding and the second-mentioned secondary winding, said second-mentioned magnetic shunt being adapted, when the second-mentioned secondary core portion has a relatively high secondary flux opposing the passage of the pr'ma-ry flux produced by the second-mentioned primary winding, to provide a negligible by-pass for the flux 1 produced by the second-mentioned primary winding, thereby causing the induction of a relatively high voltage in the second-mentioned secondary winding, and said second-mentioned magnetic shunt being adapted, when the second-mentioned secondary core portion has a relatively high secondary flux opposing the passage of the primary flux produced by the second-mentioned primary winding, to provide an appreciable by-pass for the flux produced by the second-mentioned primary winding, thereby reducing the voltage induced in the second-mentioned secondary winding with the result that the reluctance of the secondmentioned secondary core portion varies substantially inversely with changes in the resistance of the electrical load, and abalancing magnetic shunt disposed between the two primary windings, said balancing shunt being adapted, when the two secondary core portions have substant'ally the same value of secondary fiux opposing the passage of the primary flux produced by the two primary windings, to. provide a negligible by-pass for the flux produced by the two primary windings, and said balancing shunt being adapted,

when the two secondary core portions have an unequal value of secondary flux opposing the passage of the flux produced by the two primary windings, to prov. de an appreciable by-pass for the flux produced by the primary winding that is associated with the secondary winding surrounding the secondary core portion having the 'lower value of opposing secondary fiux, thereby causing a relatively small amount of the said primary flux to interlace the secondary wind'ng surrounding the secondary core portion having the higher value of opposing secondary flux and to induce a relatively low voltage therein, and

V causing a relatively large amount of the said primary flux tointerlace the said secondary winding surrounding the secondary core port on having the lower value of opposing secondary flux, and to induce a relatively high voltage in the said secondary winding and thus keeping the said secondary winding in operation for energizing its electrical load.

8. A system for transforming electrical energy to energize a plurality of electrical loads having a variable resistance comprising, in combination, a magnetic core, a secondary winding disposed to surround a portion of the magnetic core, said portion being designated as a secondaryv core portion, a. second secondary winding associated' in spaced relation with the first-mentioned secondary winding and disposed to surround another portion of the magnetic core, said portion being designated as the second secondary core portion, a primary winding associated with the secondary windings and disposed to surround another portion of the magneticcore, means for grounding one end of each of the secondary windings, means for connecting an electrical load between the grounding means and each of the other ends of the secondary windings, thus energizing one of the electrical loads by the first-mentioned second- 30 ary winding and the other electrical load, by the second-mentioned secondary winding, and two magnetic shunt means each having a relatively high reluctance and each being disposed between the primary winding and each of the secondary windings, the arrangement of the magnetic core and the magnetic shunt means being adapted such that, when the value of the secondary flux of each of the two secondary core portions opposing the passage of the primary flux is unequal resulting from an unequal load distribution upon the two secondary windings or from a short circuited condition or the like im posed upon one of the secondary windings, the magnetic shunt which is disposed between the 5 primary winding and the secondary winding surrounding the secondary core portion having the higher secondary flux opposing the passage of the primary flux, by-passes a larger amount of the primary flux than does the other shunt means, 1,)0 thereby causing less primary flux to interlace the secondary winding surrounding the secondary core portion having the higher secondary flux opposing the passage of the primary flux, and

to induce a lower voltage therein which limits the current flow through the said secondary winding having the lower resistance load or short circuited condition, and causing the primary flux to interlace the secondary winding surrounding the secondary core portion having the lower secondary flux opposing the passage the primary flux and to induce a voltage therein to keep the said secondary winding in operation for energizing its electrical load, the combined resultant operation being such that, in the event of a 5 slightly unequal load distribution upon the two secondary windings, the voltage induced in the respective secondary windings is automatically corrected to its proper value, and such that, in the event of a short circuited condition imposed 2o upon one of the secondary windings, the other secondary winding is kept in operation to energize its electrical load even though the short circuited electrical load is inoperative.

9. A transformer that is adapted to energize 5 an electrical load having a variable resistance comprising, in combination, a magnetic core having a relatively long winding portion, a primary winding disposed to surround a portion of the winding core portion, a secondary winding asso- 3 ciated in spaced relation with the primary winding and disposed to surround another portion of the winding core portion, said portion being designated as the secondary core portion, a magnetic shunt disposed between the primary wind- 35 ing and the secondary winding, said magnetic shunt being adapted 'when the secondary core portion has a relatively low secondary flux op- V posing the passage of the primary flux produced by the primary winding, to provide a negligible 1 by-pass for the flux produced by the primary winding, thereby causing the induction of a relatively high voltage in the secondary winding, and said magnetic shunt being adapted when the secondary core portion has a relatively high sec- 5 ondary flux opposing the passage of the primary flux produced by the primary winding to provide an. appreciable by-pass for the flux produced by the primary winding, thereby reducing the voltage induced in the secondary winding with the 50 result that the reluctance of the secondary core portion varies substantially inversely with changes in the resistance of the electrical load, a secondtprimary winding disposed to surround another portion of the winding core portion, a second secondarywinding associated in spaced relation with thesecond-mentioned primary winding and disposed to surround another portion of the winding core portion, said portion being designated as the second-mentioned secondary core portion, a second magnetic shunt disposed between the second-mentioned the primary flux produced by the second-men-- tioned primary winding, to provide an appreciable by-pass for the flux produced by the secend-mentioned primary windin thereby reducing the voltage induced in the second-mentioned secondary winding with the result that the reluctance of the second-mentioned secondary core 7 portion varies substantially inversely with changes in the resistance of the electrical load, and a balancing magnetic shunt disposed between the two windings of like characteristics, said balancing shunt being adapted, when the two secondary core portions have substantially the same value of secondary flux opposing the passage of the primary fiux produced by-the two primary windings, to provide a negligible bypass for the flux produced by the two primary windings, and said balancing shunt, being adapted, when the two secondary core portions have an unequal value of secondary flux opposing the passage of the flux produced by the two primary windings, to provide an appreciable by-pass for the flux produced by the primary winding that is associated with the secondary winding surrounding the secondary core portion having the lower value of opposing secondary flux, thereby causing a relatively small amount of the said primary flux to interlace the secondary winding surrounding the secondary core portion having the higher value of opposing secondary flux and to induce a relatively low voltage therein, and causinga relatively large amount of the said pri mary flux to interlace the said secondary winding surrounding the secondary core portion having the lower value of opposing secondary flux, and to induce a relatively high voltage in the said secondary winding and thus keeping the said secondary winding in operation for energizing its electrical load. I

' JAlVLES A. COMSTOCK. 

